Burning Mouth Syndrome – Vanilloid and Cannabinoid Receptors

The Endocannabinoid System and BMS

Burning mouth syndrome (BMS) is a surprisingly common condition that has no known treatment or indeed established causes. Everything in the patient’s mouth seems normal but they have a burning sensation in their whole mouth, on their lips, gums, tongue, palate, and/or throat. Symptoms also include changes in how things taste and increased thirstiness.

This study was carried out to find out whether there were differences between healthy people’s mouths and those of BMS patients in terms of endocannabinoid system receptors. There are three endocannabinoid system receptors that were looked at in this study: the cannabinoid receptors type 1 and 2 (CB1 and CB2 receptors), and transient receptor potential vanilloid channel type 1 (TRPVI). The latter is known to bind to capsaicin, the chemical that makes spicy foods “hot”.

When the researchers took biopsies, they found that there were differences in the expression of these receptors in BMS patients when compared to healthy controls. The identification of these receptors as possible causes of BMS and as avenues for therapy is exciting. More research will fill out the picture of the ECS’ role in BMS.

TRPVI, CB1, and CB2 Receptor Expression Is Different in BMS

The TRPVI receptor was already known to be responsible for human perceptions of burning and hot temperatures. It seemed like a good direction to take research into BMS, so the researchers looked for differences in TRPVI numbers in healthy and burning mouth syndrome (BMS) patients mouths.

TRPVI is a part of the endocannabinoid system and is linked to and partly regulated by CB1 and CB2 receptors, which play large roles in the regulation of inflammation. The researchers decided to look at the numbers of these receptors too so the hypothesis that BMS is inflammation related could be investigated.

The results were interesting: TRPVI and CB2 receptors were found in different locations and concentrations in the tongue samples taken from the test subjects. TRPVI and CB2 were co-localized in the tongues of BMS patients, which was not seen in healthy controls. CB1 receptor expression was lower in these areas. In addition, TRPVI was increased closer to the plasma membrane, again different to controls.

Other studies have uncovered TRPVI’s role in immune system upregulation during pain states. Neuropathic pain and inflammation all seem to show increased TRPVI expression. The authors correlate TRPVI expression with the symptoms of BMS patients. The increased expression of CB2 receptors might not be significant.

When the expression of TRPVI and CB receptors changes in the mouth, abnormal activation levels can occur, resulting in the changes to epithelial nervous cell activity that are thought to result in BMS.

BMS and Healthy Mouths Could Be Exploited for Therapies

The authors conclude that TRPVI expression correlates with BMS, leading to the conclusion that through altering the endocannabinoid system with exogenous cannabinoids, it might be possible to achieve relief of symptoms. Although it is unclear whether this will be effective at this time, it remains a possibility

The causes of the debilitating condition of burning mouth syndrome have been partly discovered. A dysregulated or altered endocannabinoid system seems to play a role and because of this, it represents a possible avenue for effective therapies, of which there are currently none.

Registered with the British Psychological Society, breaking the taboo on mental health issues is one of the driving forces in Jonathan's life. His background in biomedicine gives him additional understanding of the factors that work together to influence the human condition.